1. Field of the Invention
The invention relates to a coupling sleeve for conduit and more particularly, to a coupling sleeve designed for limited axially inward and axially outward movement on the end of the conduit section on which it is captively retained.
2. Prior Art
There are on the market conduit section and coupling sleeve combinations in which the coupling is captively held on the conduit section and which do not permit adjacent joined conduit sections to be separated from a run of conduit without the necessity of longitudinally displacing the conduit sections.
One widely employed method of joining sections of conduit involves the use of coupling sleeves having both ends threaded into which the threaded ends of conduit sections were advanced. Another method involves using a coupling sleeve which through a lock ring means is rotatably mounted to an end of one conduit and which is advanced onto the threaded end of an adjacent conduit section. The coupling sleeve is either limited to rotational motion only on the conduit or is permitted unlimited axial movement thereon. Since the prior art did not disclose the combination of the conduit section and a captive coupling sleeve which is freely rotatable and which is permitted limited axially inward and axially outward movement on the end of the conduit section, the need for the coupling sleeve of the present invention was absent. Generally, the coupling sleeves disclosed in the prior art could not be incorporated into the combination disclosed in our above identified patent applications.
Further, none of the prior art coupling sleeves are provided with annular extensions which are adapted to protect the external threads on the adjacent conduit section and which are not engaged with the threads on the coupling sleeve. Moreover, none of the coupling sleeves are constructed with spaces which would collect foreign material that is trapped between the coupling sleeve and the conduit section in order to insure the proper cooperation of the coupling sleeve with the associated lock ring means on the conduit section.
It was toward elimination of these problems that the present invention is directed.